1. Field of the Invention
The present invention relates to a vehicle body rigidity control apparatus for controlling rigidity of a vehicle body frame and the like so as to be able to obtain an adequate reactive force load, depending on a collision pattern and a collision object in a vehicle of a collision shock absorption structure.
2. Description of the Related Art
Conventionally, as a vehicle body rigidity control apparatus, there is one where rigidity of side frames to handle different collision patterns is switched over by adding resistant/promotive force for a collision load received from front of a vehicle to the side frames through piezoelectric actuators, which are provided at the side frames arranged at left/right of the vehicle (see paraphrases 0010 to 0017 and FIGS. 2 to 5 in Japanese Patent Laid-Open Publication Hei 11-291951). To be more precise, the apparatus makes the rigidity of the side frames low in a collision pattern (full-wrap collision) where a front face of the vehicle body totally collides; makes the rigidity of the side frames high in another collision pattern (offset pattern) where the collision load concentrates on one side frame; and thereby is designed to be a structure where optimum shock absorption in both collision patterns is made.
In addition, in such the vehicle body rigidity control apparatus it is also possible to control reactive force given to an object by changing the rigidity of the vehicle body, depending on not only collision patterns such as the full-wrap collision, the offset collision, and the like; but also sizes of a collision object.
However, larger power is necessary for actuating the piezoelectric actuator in order to generate the force for resisting the collision load, that is, force for directly receiving the collision load in the structure described above. Therefore, there occur problems of enlargement of the piezoelectric actuators themselves and enlargement of a battery, which supplies the power to the piezoelectric actuators.
Consequently, is strongly requested a vehicle body rigidity control apparatus that can control the rigidity of the vehicle body by smaller force.